Air admittance valve for sanitary waste pipe system

ABSTRACT

The invention relates to a valve for admitting atmospheric air into the waste pipe system in response to pressure reduction in the system for protecting the water traps in the system and to prevent atmospheric discharge of contaminated air from the waste pipe system. The valve consists of a valve body having at least two air inlet openings in communication with the atmospheric air, each of the openings alternating with a passage towards the waste pipe system, the openings and passages being equally distributed within the valve housing viewed in horizontal cross-section about the valve seat level. The valve member resting, in a normal closed position, on the valve seat separating the openings from the passages and having a substantially butterfly shaped sealing surface for a valve embodiment having two diametrically opposed openings situated perpendicular respectively to two diametrically opposed passages.

FIELD OF THE INVENTION

This invention relates to an air admittance valve to be connected to asanitary waste pipe system in order to protect the water traps in thesystem and to prevent communication between waste pipes or sewerssystems with surrounding atmosphere, said valve opens automatically toadmit outside atmospheric air into the pipe system upon presence of apressure drop within said pipe system.

A building drainage and vent system involves, in normal operatingconditions, the establishment of an induced air flow within the verticalstacks of the system due to the unsteady water downfall generated by anyappliance discharge. In order to protect the habitable space againstcontaminated odours, each appliance is normally protected by a watertrap seal. Variation due to water downfall within the drainage system,generates occasional variations in air pressure that are often capableof disturbing these water trap seals either by siphonage due to a suddenunder-pressure in the system or as a result of back pressures followingair path closures by water surcharge.

DESCRIPTION OF THE PRIOR ART

Specially designed air admittance valves have been introduced to avoidsaid inconveniences and also offers the possibility of avoiding thenecessity to vent the waste pipe system outside the roof of the buildingas said valves only open in response to sub-atmospheric pressureconditions in the waste pipe system.

Preferably, said valves are designed to assure a maximum possible airinlet flow from the air inlet of the valve to the waste pipe systemwhile passing through the temporary opened valve membrane.

The U.S. Pat. No. 4,232,706, in the name of the applicant, discloses anautomatic valve device in which a vertical tube, constituting the bodyof the valve, comprises at its upper end a constriction in the form of aVenturi which co-operates with a cover so as to form a peripheral airinlet provided with an annular valve member situated at the exterior ofthe constriction and which can be tilted when a negative pressure occursin the pipes while permitting the fresh air to penetrate into thevertical waste water pipe and which, when the pressure is equilibratedor when there is overpressure, occupies a closed position in which theescape of contaminated air is prevented.

Said valve comprises an annular peripheral opening which distributes theair inlet, in case of lifting of the annular valve member, towards thevertical tube in connection with the waste pipe. Although this devicegives generally very good results with an increased air inlet capacitydue to the venturi shaped tube, it may happen, in particularcircumstances that some turbulence may occur between the annular airinlet opening and the passage to the waste pipe. Said turbulence mayoccur when all of the air flow coming from the outer diameter of theannular valve member, in lifted position, is forced to be concentratedinto a central tube portion of the pipe system having a smaller diameterand generally a smaller section than the overall annular valve sectionand will reduce, in some extend, the air inlet capacity.

In valves of this kind, the circular or annular valve member isgenerally resting on two concentric valve seats having each a circularsealing surface. In case of deformation or distortion of the valvemember, problems could occur with the necessary airtight closure of saidvalve member with at least one of the two sealing surfaces.

An other kind of air admittance valve is disclosed in the parentdocument CH 201 565. This valve contains two diametrically opposed airinlet openings alternating with two diametrically opposed peripheralgrooves connecting the upper surface of a circular disc shaped valvemember with the waste pipe system. The air flow distribution in saidvalve is very limited, especially through the two narrow grooves, sothat this kind of valve only can be used for one single sanitaryappliance.

Patent document EP 0 409 506 discloses a valve device in which anannular peripheral air inlet is in communication with the lower face ofan disc shaped valve member through one single radial passage. Thispassage disturbs the air flow towards the waste pipe system upon openingof the valve member. Obviously, the bad distribution of the air flowpassages will create important turbulence in the air inlet and have anegative effect on the air inlet capacity of the valve.

SUMMARY OF THE INVENTION

A first object of the invention is to provide an automatic airadmittance valve avoiding as much as possible the air turbulence withinthe valve by providing a optimum distribution in the vicinity of thevalve function elements between the air inlet openings and the passagestowards the waste pipe.

A second object of the invention is to provide a well balanced valvemember shape and corresponding valve seat opening, allowing an optimumair distribution within the valve and providing a maximum lifting powerto the valve member, the valve seat having only one sealing surfacereducing the possible leakage problems of the valve member in closedposition.

A third object of the invention is to provide the interior surface ofthe valve body with a plurality of means to improve the evacuation andcollection of condensed water and to divert it into the waste pipe.

A fourth object of the invention is to incorporate grid nettingimmediately in the moulding of the valve housing, both in the air inletopenings and in the passages to the waste pipe, some of the gridelements being provided with enlarged portions in order to support thevalve member in case of overpressure or fire in the waste pipe system.

A fifth object of the invention is to provide an air admittance valvefor sanitary waste pipe systems which is easy to manufacture comprisingonly three components, each of them being directly obtain ed by amoulding process.

The above objects are achieved in accordance with the to principles ofthe present invention which are described more particularly in theannexed set of claims.

Numerous characteristics, advantages and features of the invention willappear from the following description of embodiments of the valveaccording to the invention and in which reference is made to drawings inwhich:

DESCRIPTION OF THE DRAWINGS

FIG. 1: is an exploded view of a valve according to the invention,showing the three main components;

FIG. 2 is a sectional view of an assembled valve, similar to FIG. 1;

FIG. 3: is an enlarged view of a detail in FIG. 2, in which is shown thevalve function elements, including the valve member resting on the valveseat;

FIG. 4: is a top view of the lower part of the valve body showingrespectively two air inlet openings and two passages towards the wastepipe.

FIG. 5: is a detailed sectional view along the line A—A in FIG. 4;

FIG. 6: is cross sectional view of the lower part of the valve bodyalong the line B—B in figure;

FIG. 7: is a lateral view of the lower part of the valve body seen fromarrow P in figure;

FIGS. 8 and 9: are partial sectional views along respectively the linesC—C and D—D in FIG. 7;

FIG. 10: is a sectional view in accordance with FIG. 2, but showinganother embodiment of an assembled valve according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIG. 1, the air admittance valve, according to the presentinvention, comprises a valve body 10 having a lower part comprising avertical tubular member 12 adapted to be connected to a sanitary wastepipe (not shown) being part of a sanitary waste water pipe system.

According to the invention, the upper end of the tubular member 12 has aconical shaped restriction 13 which is closed at its extremity (see alsoFIG. 2). The conical upper portion 13 of the tubular member 12 isprovided with two diametrically opposed passages 14 each of which has amoulded-in grid 16 to prevent strange objects, such as animals orinsects, to enter the waste pipe system.

The conical upper portion 13 of the tubular member 12 is surrounded byan oblong bowl-shaped housing 20, extending upwards from the tubularmember 12 and having, an upper edge 22 which is situated about anhorizontal plane H crossing the upper extremity of the conical portion13 of the tubular member 12.

The space between the bowl-shaped housing 20 and the conical portion 13of the tubular member 12 is subdivided by a partition 26 into mutuallyopposed orthogonally arranged pairs of first and second chambers.

The first pair of chambers are delimited by the partition 26 and closedsections 28 of the conical portion 13 and are in communication with thesurrounding atmosphere via openings 30 in the bowl-shaped housing 20.

The second pair of chambers are delimited by the partition 26 and thebowl-shaped housing 20 and are in communication with the lower tubularmember 12 via the passages 14 in the conical portion 13 of the tubularmember 12.

The upper edge of the partition 26 is located about the horizontal planeH and is configured so as to form a valve seat 24.

A valve member 34 is carried on the upper edge of the partition 26 andis normally seated on the valve seat 24 to isolate the first pair ofchambers 18 from the second pair of chambers 19 when the internalpressure in the waste pipe system is at least equal to the atmosphericpressure.

The valve member 34 is lifted or elevated above the valve seat 24 inresponse to a lowering of the internal pressure below the atmosphericpressure to hereby place the first pair of chambers 18 in communicationwith the second pair of chambers 19, thus admitting atmospheric air intothe waste pipe system connected to the lower tubular member 12.

The valve member 34 and the corresponding valve seat 24 have preferablya butterfly shaped form which is positioned in a longitudinal directioninside the oblong bowl-shaped housing 20.

The openings 30 in the bowl-shaped housing are also provided with a grid36 to avoid interference between the valve member 34 with any foreignobject.

According to the embodiment shown in FIGS. 1 to 6, the closed extremityof the conical portion of the tubular member 12, is provided with aclosed cavity 32 extending downwards and being arranged as a fixedfemale guiding mean for the valve member 34 which is, for that purposeprovided with a projection 35 (movable male guiding mean) having similardimensions as the cavity 32.

The valve member 34 has a particular shape so as to match with thebutterfly shaped valve seat 24 and is realised out of two differentmaterials the main part 34 in hard plastic material and the peripheralborder part 38 in soft plastic material.

These two parts being heat fused together preferably in a way asexplained in European Patent EP 0 701 504 in the name of the applicant.

Only the soft and flexible peripheral border 38 of the valve member 34is in contact with the valve seat 24 so as to obtain a tightly closedcondition when the valve member 34 is in normal closed position (seealso FIG. 3).

Means are also provided to prevent stagnation of condensed water withinthe valve housing.

As shown in FIGS. 3 and 4, the area between the upper edge 22 of thebowl-shaped housing 20 and the valve seat 24 is provided with a gutter23, the bottom of which is rounded so as to facilitate the evacuation offalling drops of condensed water towards the tubular member 12 connectedto the waste pipe system.

In order to improve the air inlet flow, the grid 36 of the openings 30are made of elements having an aerodynamic or droplet-like crosssection, as can be seen in FIGS. 8 and 9 of the drawings.

Preferably, at least two of said grid elements 37 are provided with anenlarged flattened upper region so as to support the valve member 34 incase heavy overpressure occurs in the waste pipe system. Also in case offire in the waste pipe system, the fire resistant main part of the valvemember 34 can be supported by the grid elements 37. Indeed, due to thesoft and flexible outer edge 38, the valve member 34 could be drawndownwards and could be stuck beneath the level of the valve seat 24 incase of heavy overpressure or fire in the waste pipe system.

Of course, it is also be possible to provide the elements of the grid 16of the passages 14 with a aerodynamic drop-like shaped cross section.

Finally, the valve body 10 is closed with an upper lid 40, closing theupper edge 22 of the bowl-shaped housing 20 in a complete air-tightmanner.

The side walls 42 of the upper lid 40 are slightly conical with the samepurpose to facilitate the evacuation of condensed water. For the samereason, the upper wall of the lid 40 is slightly rounded and the innersurface of said wall are provided with radially arranged ribs 44 toevacuate the condensation of water towards the periphery.

In case the pressure in the waste pipe drops below the atmosphericpressure, the valve member 34, which lower surface is in communicationwith the atmospheric air pressure and which upper surface is incommunication with the waste pipe pressure, will promptly be tiltedupwards, allowing the atmospheric air to enter through the openings 30and the vertical gap, created between the valve seat 24 and theperipheral border 38 of the valve member 34, towards the passages 14 ofthe tubular member 12 and into the waste pipe system.

The valve according to the invention and in particular the specialbutterfly shaped surface of the valve function elements, i.e. the valvemember 34 and valve seat 24, provide a maximum lifting power of thevalve member on the one hand and a well balanced distribution of the airflow passage within the valve body on the other hand.

In order to obtain said well balanced distribution of the air flow, itis important that the total surface of the air flow passage area throughthe open valve function elements 24, 34 is substantially equal to thetotal surface of the air inlet openings 30.

For an optimum valve capacity it is also important that the totalsurface of the air flow passage through the open valve function elements24, 34 is substantially equal to the total surface of the passages 14from the valve function elements towards the waste pipe system as wellas to the inner surface of the tubular member 12.

To improve the function of the valve and in particular the lifting powerof the valve member 34 from its seat 24, it is also important that theratio between the total surface inside the periphery of the valve seat24 and the total surface left between the seat 24 and the inner side ofthe bowl-shaped housing 20 (representing the possible depression zone)is preferably less than 1.

In case more than two openings are to be provided, alternating with morethan two passages, the shape of the valve seat and corresponding valvemember will have to be adapted. Instead of a butterfly shaped valvemember one could obtain a triangular or shamrock shaped valve member.

Another embodiment of the invention, representing another possibleguiding arrangement of the valve member, is shown on FIG. 10.

According to said embodiment the inner surface of upper lid 50 isprovided with at least two projections 52 (fixed male guiding means)extending downwards until about the horizontal level H, and engagingcorresponding cavities 62 (movable female guiding means) are provided onthe main part of the valve member 64.

Upon occasional lifting of the valve member 64, said valve will beguided with its cavities 62 by means of the projections 52 fixed ontothe upper lid 50. In this case the air inlet flow will even be increasedbecause the guiding, cavities 62 will retract themselves partly awayfrom the air inlet flow during the lifting of the valve member 64.

In order to improve the guiding characteristics, the projections 52could also be made out of metal.

According to this invention, the guiding of the valve member during thelifting up and lowering sequence, can be obtained either by means of afixed female guide 32 and a male guide 35, which is part of the valvemember, or by means of fixed male guides 52 and movable female guide 62incorporated in the valve member.

Tests have shown that the capacity of the valve according to the presentinvention has significantly improved with respect to the existing airadmittance valves.

The purpose of the embodiments described herewith is only to illustratethe invention while still other variations are possible without fallingout of the scope of the invention as expressed in the following claims.

LEGEND OF THE REFERENCE NUMERALS

10: lower part of the valve housing

12: tubular member

13: upper conical portion of 12

14: passages towards the upper part of the valve

16: passage grid

18: first pair of chambers

19: second pair of chambers

20: oblong bowl-shaped housing

22: upper edge of the housing 20

24: valve seat

23: gutter

26: partition

28: closed sections of the conical portion 13

30: air inlet openings

32: cavity

34: valve member

35: projection (male guide)

36: air-inlet opening grid

37: supporting grid element

38: peripheral border of 34

40: upper lid

42: side wall

44: ribs

50: upper lid

52: guiding projections

62: cavities (female guide)

64: valve member

What is claimed is:
 1. Air admittance valve adapted for connection to asanitary waste pipe system having a waste pipe and water traps, the airadmittance valve providing for admitting atmospheric air into the wastepipe towards valve function elements of the valve in response to apressure reduction in the system in order to protect the water traps inthe system and to prevent discharge of contaminated air from the systemto the atmosphere, the valve comprising a valve body including valvefunction elements and having: a vertical tubular member adapted to beconnected to the waste pipe, the tubular member having an inner spaceand including an upper section which tapers inwardly and upwardly sothat the cross section diminishes at an upper end of the upper sectionto present an upper conical portion; at least two passages provided inthe upper conical portion which communicate air from the inner space ofthe tubular member towards the valve function elements; a cover memberoverlying said upper section and having a top wall spaced above theupper end of the tubular member; the valve function elements including avalve member situated between the upper end of the tubular member andthe top wall of the cover member, said valve member resting on a valveseat having a sealing surface situated at a level in an horizontal planepassing near the upper end of the tubular member and being freelymovable upwards from the valve seat, said valve member having an uppersurface and a lower surface; and at least two atmospheric air inletopenings being in communication with the lower surface of the valvemember, while the upper surface of the valve member being incommunication with the waste pipe system through the at least onepassage so as to close said valve member when the pressure in the wastepipe equals or exceeds atmospheric pressure and to open said valvemember in order to create an atmospheric air flow passage into the wastepipe when the pressure in the waste pipe is less than the atmosphericpressure, wherein the valve body further comprises an oblong bowl-shapedhousing and a partition subdividing the interior of the bowl-shapedhousing into mutually opposed orthogonally arranged pairs of first andsecond chambers, the first pair of chambers being in communication withthe surrounding atmosphere via said openings which are provided in thehousing and said second pair of chambers being in communication with thelower tubular member and the waste pipe system via the passages in theupper conical portion of the tubular member.
 2. Air admittance valveaccording to claim 1, wherein the first pair of chambers and the secondpair of chambers are equally spaced in a horizontal cross section so asto obtain a well balanced air flow within the valve body.
 3. Airadmittance valve according to claim 1, wherein the air inlet openingsare arranged in the bowl-shaped housing located outside the conicalportion of the tubular member, the housing having an upper edge situatedabout the valve seat level.
 4. Air admittance valve according to claim1, wherein the valve function elements comprising the valve seat and thecorresponding valve member have a substantially butterfly shaped sealingsurface which is positioned in a longitudinal direction with respect tothe oblong valve body.
 5. Air admittance valve according to claim 4,wherein the ratio between the total surface within the substantiallybutterfly shaped valve seat sealing surface and the total surface leftbetween the seat and the inner side of the bowl-shaped housing,representing the possible depression zone, is less than 1 so as tocreate a maximum lifting power of the valve member from the valve seat.6. Air admittance valve according to claim 1, wherein the total surfaceof the air flow passage through the open valve function elements issubstantially equal to the total surface of the air inlet openings andsubstantially equal to the total surface of the passages from the valvefunction elements towards the waste pipe system.
 7. Air admittance valveaccording to claim 1, wherein the total surface of the air flow passagethrough the open valve function elements is substantially equal to theinner surface of the tubular member.
 8. Air admittance valve accordingto claim 1, wherein the housing of the valve body is provided withpartitions subdividing the interior of the housing so as to obtain asubstantially equally spaced and balanced air flow distribution withinthe body between the atmospheric air inlet opening and the passagetowards the waste pipe system when the valve member is in an openposition.
 9. Air admittance valve according to claim 1, wherein theupper conical shaped portion of the tubular member has an extremitywhich is closed and is provided with at least two peripheral passagesleaving between them closed sections.
 10. Air admittance valve accordingto claim 1, wherein the housing has an outer wall and wherein the valveseat comprises one continuous sealing surface which extends downwardswith a partition delimiting the space inside the outer wall betweenrespectively the passages and the closed sections of the conical portionof the tubular member.
 11. Air admittance valve according to claim 1,wherein the valve member is provided with a male guiding meansco-operating with a fixed female guiding means provided in the body. 12.Air admittance valve according to claim 1, wherein the valve member isprovided with female guiding means co-operating with fixed male guidingmeans provided on the cover member of the valve body.
 13. Air admittancevalve according to claim 1, wherein the valve body has an inner surfacewhich is provided with a gutter, conical side walls and radiallyarranged ribs for improving the evacuation of condensed water.
 14. Airadmittance valve according to claim 1, wherein the valve member is madeout of at least two different materials, a main part of the valve memberbeing made out of hard, fire resistant material and a peripheral borderpart of the valve member being made out of a relatively softer, flexiblematerial relative to material of the main part.
 15. Air admittance valveaccording to claim 1, wherein the openings and the passages arerespectively provided with grids.
 16. Air admittance valve according toclaim 15, wherein the grids are made with elements having anaerodynamic, substantially droplet-shaped cross section.
 17. Airadmittance valve according to claim 15, wherein the grid comprises aplurality of grid elements, at least two of said grid elements beingprovided with an enlarged, flattened upper region capable of supportingthe valve member in the event of overpressure or fire in the waste pipesystem.